Heat exchanger



Jan. 8, 1935. G. DLEN E1' AL 1,987,182

' HEAT E'XGHANGER med Mayu. 1932 ..g'swnms-sheet 1 mvEN'roRs wfg@ BY#eff-A oRNEY I JUL 3, 1935 G, DALEN ET Ax. 1,987,182

HEAT EXCHANGE'R Filed May 24, 1952 3 Sheets-Shea?I 2 INVENTQRS l Jan. 8,1935. G, DALN Er Al.

HEAT EXCHANGER Filed May 24, 1932 3 Sheets-Sheet 5 INVENToRs BY de#e/rATToRNEY Patented Jan. 8, 1935 l UNITED STATESg PATENT ori-ics HEATEXCHANGEB Gusta! Daln and Gustaf Erik Bjrklund, Lidingo, weden,assigner-s `to Svenska bolaget asaccumulator, Stockholm, Sweden, acorporation of Sweden Application May zi', 19:2, serial No. 613,230 InSweden September 25, 1931 18 Claims. (CL 122-43) The present inventionrelates to heat exchange of circulation and of heat transmission in a cosed and has particular reference to heat exchange circuit for heattransferring fluid; to provide, in lsystems wherein heat is transferredindirectly a domestic hot water supply system, indirect heatfrom asource of heat to the body to be heated ing means in which the flow ofheatytransmitting through the medium of heat transmitting fluid fluid isautomatically governed within the path 5 circulating in a closed path inwhich it is vaof flow of the fluid in accordance with the rate porizedat the source of heat and condensed by of condensationdue to themomentary requiredelivering 'heat to the body to be heated. y ments ofthe domestic supply to be heated; to

More particularly, the invention relates to improvide an indirectheating system in which va- 1o proved method and means for governing therate por is generated in a relatively even manner and 1o at which heatis transferred by the circulating at a rate not exceeding therequirements of the fluid in accordance with the momentary heatresystem; and to provide an indirect heating sysquirements of the bodyto be heated. y tem of the character described in which auto- Theinvention is particularly useful for the matic regulation of the rate ofvapor generation :5 purpose of heating a, supply .of hot water for doandof heat transfer through the system is ef- 15 mestic purposes with heatderived from a confected by a restriction in the path of circulationtinuously fired domestic cooking stove of the heat of the heattransferring medium. Other objects accumulating type, such as isdisclosed in U. S. of the invention will appear in thedesoription toPatent No. 1,559,162 granted October 27, 1925 on "follow,

the application of Gustaf Dalen, but it is to be For purposes ofillustrating the invention, we 20 understood that the invention isapplicable in have shown in the accompanying drawings a other elds inwhich the body to be heated may number of forms of apparatus of the typedesigned be fluids other than water, or solids, and the to provide asupply of hot water for domestic source of heat may be of anyfsuitablecharacter. uses, such supply being heated from 'a domestic In domesticwater `heating installations of the stove of the accumulating typedisclosed in the y2,15 above mentioned character, water is advantapatentabove referred to.k Itis to be understood, geously used as thecirculating heat transmitting however, that the apparatus shown in thedrawfiuid but other uids may be employed, particuings is illustrativeonly and that the invention is larly in cases where the temperaturelevel of the not to be limited to the general type of apparatus body tobe heated is such that a fluid having a disclosed but may equally wellbe utilized in other` 30 vaporizing temperature above or below thevaporforms of apparatus employed for other purposes. L izing temperatureof water is suitable. In the drawings:

Among the several objects of the invention are: Fig. l is a more or lessdiagrammatic vertical to provide indirect heating apparatus in which asection of va .domestic water heating apparatusr ,f heat transferring.fluid isfcirculated and alterembodying theV invention;v

l 35 nately vaporized and condensed in a closed path Fig. 1a is aview onan enlarged scale of part of of circulation and is permitted to havesubstanthe apparatus shown in Fis. l; tially unrestricted opportunity toexpand upon Fig. 2 is a view similar to Fig. 1 showing anvaporization ofa portionl of the fluid; to provide other type of the apparatus:

40 indirect heating apparatus of the characterre- Fig. 3 is a viewshowing schematically another 40 ferred to in which a closed circuit forcirculation form of apparatus of the illustrated in Fig. 1; of heattransferring fluid is connected at a point Fig. 4 is a view, on a largerscale, showing part in the circuit where the uid is in liquid form to ofstili another type of apparatus. an expansion line adapted toy contain avariable Referring now to Fig. 1 of thedrawings, referquantity 0f fluid,dependinsgupon the k8.11101111' 0f ence numeral 10 indicates a `hotwater storage 45 fluid forced from the circuit of circulation due tosupply tank for a domestic or like supply, from` vaporization of uidtherein, and to maintain a which hot water is withdrawn through pipe 11static pressure of liquid head on said circuit; to and to which wateris. supplied by pipe 12. Tank provide indirect heating apparatus forautomatif' 10 is preferably covered by a layer of insulating callyraising the temperature of a body.. t'o:.`be material 13 to preventundue loss of heat by radi- 50 heated to a desired temperature levelandthereation.

after automatically maintaining such" body at a Situated within tank 10,preferably in the lower temperature level no't exceeding thedesired tem-4portion thereof, is the pipe coil 14, from the upper perature; toprovide, in anin'direct heating sysend of which the pipe 15 passesthrough a suittem, means .for .automatically governing the rate ableclosure 16 in the bottom of the tank and from 55 the lower end of whichthe pipe 17 passes through closure 16 to the exterior of the tank. Fromthe highest point of pipe 15 the pipe V18 leads to the exterior of thetank, this pipe being provided with a shut-off valve 19 outside of thetank.

Pipes v15"and 17 are connected at their lower ends to the upper andlower ends, respectively, 'of a coil 20 surrounding the combustionchamber casing 21 of a cook stove of the accumulator typeindicatedgenerally at 22. 'Ihis stove comprises an annular heataccumulating member 23,

the lower skirt portion 24 of which extends into an annular refractoryilre box 25 within vthe casing 21. Removable covers 26 and 27 permit'theintroduction of solid fuel into the magazinespace 28 within the skirt 24and the fuel is burned on a grate 29. Air is admitted through anysuitable opening below grat`e\29,.and the combustion gases pass throughthe annular ilue space 30 to the stack or chimney indicated at 31.

As will be evident fromA the drawings, coils 14 and 20 andfpipes 15and-17 constitute a-closed circuit designated generally by referencenumeral 32. Coil 2 0 may be said to constitute a vapor generator andAcoil 14to constitute a condenser for condensing vapor generated in coil20. In this level indicated at,40.

circuit a trap adapted to be fllled with liquidy at all times isprovided by the elbow 33 at the 'lower end of pipe 17, this elbowextending below the lowest partot the coil 20. Connected to the lowestpoint in the circuit 32 is the pipe 34 which at its lower endadvantageously terminata in a depending loop or elbow 35 and at itsupper end is connected to the lower portion of the receptacle 36.Receptacle 36 is advantageously above the highest level of the circuit32 and may be in open communication with the atmosphere through asuitable vent 37. The receptacle 36 may con veniently be mounted on topof the tank 10 as illustrated. A restriction providing an oriilce 38 vofsmall diameter is preferably provided in the pipe 34.y f

Turning again to the circuit 32, a restriction 39 providing an nriiiceof small diameter is provided in the circuit, this orifice lbeingadvantageously located in the elbow 33 between coil20 and pipe 34.

The operation of the apparatus isas follows, it being assumed vthat thetank 10 is illled with water to be heated. v

'I'he circuit 3 2 is lled with water through the receptacle 36 and thepipe 34, the flow of water into the closed circuit from the lowest pointthereof being permitted by opening valve 19 to vent the trapped air fromthe' highest point in the circuit through pipe 18. Preferably the systemis illled until the water reaches a height such that the receptacle 36is partially filled. as to the vIf, now, fuel is burned in the stove 22,heat is ansmitted to coil 20 by conduction and Vradiation from theadjacent parts providing the ilre space in the stove and steam isgenerated in this coil. 'I'he steam generated passes upwardly throughpipe l5 from pipe 15 and coil 14. The water displaced by the generationof steam ows into pipe 34 and thus to the receptacle 36 which acts as anexpansion tank. Due to the tal cross-sectional area of the receptacle36, the water forced into this receptacle by expansion in the closedcircuit does not materially alter the height of the water level 40 sothat the variation in static pressure due to head of liquid on thesystem is substantially negligible and the system into` coil 14,displacing water.`

relatively large horizon-r.

can be considered for all practical purposes as operating under constantpressure.

The steam which passes to the coil 14 is condensed by delivering itsheat'to the 'water in tank 10 and the condensate from coil 14 returns tothe 5 lower end oi'- coil 20 through the return or drain pipe 17.Circulation of steam through the system is eilected due to thedifference inthe weight of the column of water in pipe 17 and the weightof the column roi' steam in pipe ,15.

'I'he heat absorbing'area of the coil 20, which governs the rate ofvaporization of water in the circuit and the area provided by coil 14for the condensation of steam, may be calculated in accordanceI withvwell known principles of heat l5 transmission so that the rate at whichheat is supplied to the water in tank 10 and consequently the rate atwhich'a tank o! cold water can be brought to desired temperature, meetsthe re quirements of the` individual installation. 20

During periods when cold water is being heated in the tank 10, all ofthe steam generated in coil 20 should be condensed in the coil 14 sothat there is a liquid column in pipe 17 for-the full height thereof.thereby providing the maximum 25 speed of heat transfer.

i As the temperature of the water in tank 10 rises, the rate of heattransfer through the walls of the pipe coil 14. decreases and the rateof steam condensation accordingly decreases. is higher than the rate ofcondensation in coil 14,

a certain amount of steam will pass through coil 14 without beingcondensed and as a result. the height of the liquid column inthevreturnI pipe'17 will be decreased. This will operate toreduce 35 thehydrostatic head eilecting circulation and will accordingly slowdown therate oi' circulation. Thus the rate ofvaporization also will bevvdecreased. It will be evident that variations in i the quantity of waterin the closed circuit 32 will 40, produce variations in the amount of-water in receptacle 36 and will also produce reversals of'ilow in pipe34.

Assuming that the condenser and generator are both steam illled, it isimportant to prevent un- 45 restricted ilow of a solid column or iet oi'water into the generator coils since if this were permitted, aconsiderable amount of water might flow into the generator in such amanner as to be ilashed into steam, thereby producing explosive 50action ofv a nature causing violent surges and water hammer in thesystem. In order to minimize such surges, the small oriilce 38 is pro--vided in pipe 3,4, this orifice acting as acheck and another smallorifice 39 is provided for the 55 same eilect in pipe 17. g I "1 Byconnecting the expansion line into the elbow` n 33 at the lowest part ofthe closed circuit 32, it will be evident lthat expansion ofthe fluid inthe closed circuit will operate to force water and not 00 steam fromthis circuit into the expansion line. It is one of the objects of thepresent invention to provide apparatus which will automatically raisethe temperature of the water in tank 10 to a predetermined desiredlevel-and thereafter maing5 tain the temperature of the water at asubstant tially constant level. In a' domestic hot/water system thistemperaturelevel is below the temperature of the stesmb'eing. condensedand in, theevent that water is not withdrawn from tank 70 10 for anextended period the amount of heat supplied to the water in this tankshould just -coxnpensate for the radiation losses if the temperature ofthe water is to be kept from exceeding the predetermined deslred leve Ifthe rate of vaporization in coil 20 am.

. I the pipe 15' and with a small orifice 44 aifording This control oftemperature in the tank as above mentioned is effected according to thepresent invention by automatically 'altering the rate of circulation inthe closed system 32 in accordance with the rate at which steam iscondensed in the coil 14.

. Turning Vnow to Fig. 2, there is illustrated another form ofapparatus, according to the invention. It has proved convenienttoconnect the expansion pipe 34'pto pipe 1'1 at a point close to thetank 10. This arrangement, vamong other things, facilitates the removalof air from the circulating system. To eliminate the fear of gettingvapor into the'expansion pipe the leon--V denser is formed in a specialmanner.' The steam generated in coil 20 is carried upwardly through apipe 15' which terminates at its upper end in the upper portion of acondenser comprising a closed cylinder 40a. Cylinder 40a is divided by adiaphragm 41 into an upper chamber 42 and a lower chamber 43. Diaphragm41 is provided restricted communication between the two chambers. Toenable the circulating system 32 to be filled, pipe 18' is provided,this p ipe being in communication with the upper portion of chamber 42.Flow through this pipe is controlled by means of the valve 19 locatedoutside of tank 10.

Cold water is admitted to tank through the inlet pipe 12' and hot wateris withdrawn through the pipe 11. 1

The expansion receptacle 36' is connected to the return pipe 17' by thevpipe 34', but as will' be observed from the il'gure, pipe 34 isconnected into the closed circuit 32 at a higher level than in thearrangement shown in Fig. 1 andthe restriction 39 is placed in the pipel'I' below the point where pipes 17' and 34 join. The restriction 39'prevents too rapid flow of water to the generator from either the supplyin the expansion line or the supply in the lower portion of thecondenser.

The function of the diaphragm 41 and the orifice 44 is to prevent vaporfrom entering the expansion pipe 34'. This is accomplished by thethrottling effect of orifice 44. It is a known fact that an oriilcetransmits a weight of vapor, which isapproximately only .03 o f theweight of water, transmitted by the same orifice andat the samedifference of pressure, assuming that the vapor has a temperature of 100C. and substantially atmospheric pressure.

The vapor generated in generator 20 rises in displaces a certain amountof water in the chamber 42 of condenser 40.I If the water in tank 10 isrelatively cold, rapid condensation takes place. The water level inchamber 42 is determined by the temperature of the water in tank 10 insuch manner, that the rate of condensation of the upper part of chamber42, above the water level, is enough tocondense the vapor from thegenerator 20. When the temperature of water in tank 10 increases, therate of condensation decreases. The balance between generating andcondensing is maintained by the water level in chamber 42 sinking. At apredetermined temperature of water in tank 10, the water level inchamber 42 reaches the diaphragm 4l, and if now the temperature ofywater in tank 10 furthermore increases, the water level tends to sinkbelow the diaphragm 41. In this case the upper part of chamber 43 alsowill contain vapor, which has to pass through orifice 44. Thethrottling' effect of theoriflce 44 now takes place of circulation inthe circuit 32 decreases thereby causing less vapor to pass from thegenerator to the condenser. In this way the heat transmissionautomatically slows down.

.The condensing eillciency of the lower chamber 43 of condenser 40ashould be great enough to condense all vapor, passing through the orice44, thereby preventing vapor from entering the pipe 34. l

Turning now to Fig. 3, there v`is illustrated schematically anotherarrangement, in which the expansion pipe 34 is connected to the returnpipe 17 close to the condenser 14. To prevent the vapor from f enteringthe receptacle 36 another condenser 14a is arranged in the lower part ofthe expansion pipe 34. If any vapor should enter the pipe 34, it will becondensed in condenser 14a, giving up its heat to the'water in the tank10.

Another feature of this arrangement is, that if air should have enteredthe system, for example by entrainment or absorption in the water inthesystem, this air will collect incondenser 14, there mixing with vapor,and slowing down the rate of condensation. When tank 10 isv at hightemcondenser 14 and so causes vapor mixed with air to enter the pipes1'7 and 34. The vapor and the air` rise to condenser 14a, where thevapor condenses. The air continues `to rise through pipe 34 and leavesthe system by way of receptacle 36.v Inthis way from time to time theair will automatically be expelled from the system, thus ensuringcontinuous heat transmission.

In the figure, 20 indicates the generator, connected to the vreturn pipe17 and toA the steam pipe 15.

One orifice 38 is arranged in the expansion pipe 34 and another orifice'39 in the lowest part of return pipe 17. The function of these orificesis. the same as before mentioned in connection with Figs. 1 and 2.

Turning now to Fig. 4 there is illustrated on an enlarged scale aportion of an apparatus of preferred commercial form. In the arrangementshown in this figure, the condenser 14 is of the coil type illustratedin Fig. 1 and is located at the bottom of a tank 10a having an outletpipe 11a and inlet pipe 12a. .f

Coil 14' is divided into upper. and lower portions 14b and 14c,respectively, and the portion of the steam supply pipe 15a. inside ofthetank is preferably insulated spaced from this portion of pipe 15a toprovide an insulating chamber 46 between the two pipes. This arrangementminimizes condensation of steam at a pointin the system such that thecondensate will have to return through the upflow pipe 15a.

'Ihe two portions o the condenser 14h and 14c are joined through arestriction which' instead of being provided by one small orifice isprovided by a plurality of orifices in series which, in the present formof the apparatus are held in position in the closure member 16a by meansof the cap 48 and spring 49.

'The mpmeet pox-uen e: the condenser n ventedwhich flow may be becontrolled by an external cock or a removable plug 51.

Betweenl the discharge end of the-coil forming by means ofa sleeve 45the portion 14o of the condenser and the return line' 17a there isplaced a second restriction 52 1 scribed. The restriction provided at 47provides vwhen the rate of condensation is low, thesteam Y thedesiredresistance to flow oi' steam at a point intermediate the ends oi'the condenser so that which does pass through the restriction 'iscondensed in the lower portion I4c oi' 4the condenser. The restriction52 provides" the necessary resistance to prevent unduly rapid dow ofwater to the generator so that hammering in the system due to rapidlocal generation ot steam in the generator .is avoided.

It has been found in practice that a satisfactory form of apparatusisone in which the difierential pressure or liquid head tending tomaintain circulation in the syste'm is provided by a column (assumingwater to be the liquid circulated) having a height of approximately .08of a meter, and in which the restriction to iiow provided in the closedcircuit is such that the restriction is capable oi' passing, under theexisting pressure conditions, only a small fraction of the weight oi'steam as compared with the weight oi' water which it will pass. When therestriction takes the form of an orifice, an orifice of 0.6 of amillimeter has been found satisfactory in operation, an oriiice of thissize being capable of passing, in the form of steam, only about 3% ofthe weightof fluid which it will pass in the form of water. Instead ofone orifice with a very small opening, in Fig. 4 there is shownva seriesoi' 6 orifices with a diameter of 1.2 m/m. this series of orificestendling to provide the same throttling effect as that provided by asingle orifice of very much smaller diameter.

The expansion line may be open to atmosphere or not as desired and,obviously, this yexpansion line need not comprise a separate pipe andtank but may be formed by a pipe alone. provided the pipe has sufficientcapacity to take care oi' the desired expansion.

If water is used as the heat transmitting medium, the liquid in theexpansion line may advantageously be covered by a layer of some lighterliquid such as oil which will act to prevent evaporation of the waterand will also act to prevent the absorption of air by the water. k

If the temperature to which it is desired to heat the body to be heatedis greater than the Vaporizing temperature of the heat transferringfluid at about atmospheric pressure, the latter iiuid may be maintainedunder any desired pressure in order to raise itsr vaporizing temperatureby connecting the. expansion line, which in this instance would beclosed to the atmosphere, to any suitable source of fluid pressure.Variations in the pressure to which the heat transferring fluid issubjected may also be effected by varying the heightof the liquid columnin the expansion line.

From the foregoing description, it will be evident that in accordancewith the present invention automatic control of the rate of heattransi'er to the body to be heated is effected in response to variationsin the temperature of the bodyto be heated by the direct influence ofthe heat ,ab..

sorbing capacity of the body to Ibe heated and .without the intermediaryof auxiliary regulating mechanism, so that the apparatus provides theim-j prising a source of heat., a tank adapted to con-- tain a body tobe heated, means providing a closed circuit for circulating a heattransferring fluid between said source and said tank, said meanscomprising'a vapor generator adjacent to said source, a condenser-insaid tank, a conduit for conducting vapor from the generator tothecondenser and a return line for conducting condensed vapor from thecondenser to the generator said `returnlixie having a restrictiontherein of less cross-sectional area than the minimum cross-sectionalarea of said vapor conducting conduit, and expansion means associatedwith said return line between said condenser and said restriction.

2. Apparatus oi' the character described `comprising a source of heat, atank adapted to contain a body to be heated. means providing a closedcircuit tor circulating a heat transferring fluid between said sourceand said tank, said means comprising a vapor generator adjacent to saidsource, a condenser in said tank, fa conduitior conducting vapor fromthe generator to the condenser and a return line `for conductingcondensed -vapor from the condenser to the generator, and

an expansion line connected to said return line, said return line havinga restriction therein between the generator and the connection Sto theexpansion line providing a smaller cross-sectional area in saidreturnvline than anywhere in the vapor conducting conduit, and saidexpansion line having a restriction therein.

3. Apparatus of the character described comprising a source oi' heat, atank adapted to contain a body to be heated,` means providing a closedcircuit for circulating a heat transferring fluid between said sourceand said tank, said means comprising a vapor generator adjacent to saidsource, a condenser insaid tank, an upfiow.

anywhere in said upfiow conduit. and an expansion line'connected to theyretiu'n line between the restriction and the condenser.

4. Apparatus of the character described comprising a stove of the typeintended for continuous operation, a tank for heating water, meansproviding a closed'circuit for circulation oi' a heat transferringfluid, said means comprising a vapor generator arranged to be heated bysaid stove, a condenser located in said tank, an upflow conduit forconducting vapor from the generator tothe condenser, a return line forconducting condensed vapor from the condenser to the generator and anexpansion line connected lto the return 1in'e,.|sai\d return line havinga reduced crosssection of less area than the smallest cross-sectionalarea in said upiiow conduit and said expanf sion line being connected tothe return line between the condenser and the place oi' reducedcross-sectional area. Y l

5. Apparatus of the character described comline providing` a smallerarea of now in said return line than 25 means for maintaining a 55parts, and an expansion line connected to prising means providing aclosed circuit for circulation of a heat transferring fluid, said meanscomprising a vapor generator, a condenser, an upflow conduit forconducting vapor from the 5 generator to the condenser and a return linefor conducting'condensate from the condenser to the generator, anexpansion line connected to said return line, means for applying heat tosaid generator, means for maintaining a body to be heatl ed in heattransfer relation with said condenser, and a restriction in said returnline between the generatorand the connection to the expansion lineproviding a smaller cross-section for iiow in said return line thananywhere in said upfiow 15 conduit for governing the rate ofV admission0f liquid to said generator.

6. Apparatus of the character described comprising means providing aclosed circuit for circulation of a heat transferring fluid, said means20 comprising a vapor generator, a condenser, a conto the condenser anda return line for conductling condensate from the condenser tothegenerator, means for applying heat to said generator,

body to be heated in heat transfer relation with said condenser, meansin said circuit for automatically governing the rate of circulation ofthe heat transferring iiuid therethrough in response to variation in therate 30 'of condensation of vapor in' said condenser, said last namedmeans comprising arestriction located within the condenser so that onlycondensate passes therethrough when the rate of condensation in thecondenser is relatively high and vapor 35 `and condensatepasstherethrough when the rate of condensation in the condenser isrelatively low and an expansion line connected to the returnline.

7. Apparatus of the character described com- 40 prising means providinga closed circuit for circulation of a heat transferring fluid, saidmeans comprising a vapor generator, a condenser, -a

conduit for conductingvapor from the generator to the condenser and areturn line for conducting 45 condensate from the condenser to thegenerator,

/ means for applying heat to said generator, means for maintaining abody to be heated in heat transfer relation with said condenser, meansin said circuit for automatically governing the rate of 50 circulationof the heat transfer fluid therethrough in response to variation in therate of condensation of vapor in said condenser, said means comprising'a restriction in said circuit located so as to divide the space withinthe condenser into two the return line. 1

8. Apparatus of the character described ccmprising means providing aclosed circuit for circulation of a heat transferring fluid, said means60 comprising a vapor generator, a condenser, a conduit for conductingvapor from theA generator to the condenser and areturn line forconducting condensate from the condenser to the generator, means forapplying heat to said, generator, means 65 for maintaining a body to be,heated in heat trans .-A .l in said" fer relation with said condenser,means circuit for automatically governing the rat of circulationA pf'the Yheat transfer fluid there,

through in response to 70 condensationlof vapor in said condenser, saidmeanscomprising a restriction in said circuit lo`- cated so as to dividethe space within the condenser into two parts, an expansion lineconnected to said return line, and a restriction in the return 75 linebetween .the expansion line and the generator.

vto the condenser and Vgenerator with the upper end variation in" vthe-viate of 9. Apparatus of the character described comprising meansproviding a closed circuit for circulation of a heat transferring fluid,said means comprising a vapor generator, a condenser, a conduit forconducting vapor from the generator a return line for conductingcondensate from erator, means for applyingheatto said generator, meansfor maintaining a body to be heated in heat transfer relation with saidcondenser, means in said circuit for automatically governing the rate ofcirculation of heat-:transfer fluid therethrough in response .tovariation in the rate of condensation of vapor in said condenser, saidmeans comprising an oricel insaid return line adjacent to the outlet ofsaid condenser, and an expansion line connected to the return line at apoint between the condenser and the orifice.

10. Apparatus of thelcharacter described'comprising a source of heat, atank adapted to conduit for conducting vapor from the generator 4 ti'bOdYf fluid t0 be hefted. means Providing a 'closedcircuit for a heattransferring fluid, said means comprising a vapor generator arranged tobe heated by said source ofheat, a condenser comprisingv a pipe coillocated in said tank, a conduit forv vapory connecting the upper portionof said return line connecting the lower end of said pipe coil to thelower portion of 'said generator and a restriction in said pipe coilintermediate its ends, and an expansion line connected to said returnlin'e. Y y

- 1. Apparatus of the lcharacter described comprising a source ofheat,-a tank adapted to contain a body of fluid to be heated, meansproviding a closed circuit for circulation of a heat transferring fluid,said means comprising a vapor generator arrangedA to receive heat fromsaid source, a closed vessel in said tank, means having an orificetherein for dividing the interior of said vessel into an upper and alower chamber, a conduit for conducting vapor from said generator tosaid upper chamber and a return line for conducting condensate from thelower chamber to the generator, and an expansion y connected to saidreturn line. l

12. Apparatus of the character described comprising a source of heat, atank adapted to contain a body of fluid to be heated, means providing aclosegcircuit for circulation of a heat transferring fl d, said meanscomprising a vapor generator arranged to receive heat from said source,a closed vessel in said tank, ilow restricting means in said vessel, aconduit for conducting vapor from said generator to said vessel, areturn line for conducting condensate from the lower portion of saidvessel to said generator anda restriction in said return line of smallercross,- sectional area than the minimum cross-sectional area of saidvapor conducting conduit, and an expansion line connected to the returnline between4 said last-mentioned restriction and said vessel.

\ 13. n'apparatus of thewhrractelr'dllcibled. 'a

closed circuit for circulation of-mreheat transferring iiuid comprisinga condenser having a second portion from which condensate is withdrawn,and a connection between said portions comprising a number of holes inseries for restricting ilow of vapor from said ilrst to said secondportion.

14. In apparatus of the characterdescribed, a tank adapted to containfluid to be heated, a condenser for heating iluid located in the lowerof said pipe coil,a

the condenser to the gen- ,.rst portion to which vapor is admitted and al I portion to the upper part `contain num to be heated'.

- cross-sectional area o! now `portion ot ksaid tank, said condensercomprisingv a pipe coil'dlvidcd'into an upper portion and alower'portion, a conduit for conducting vapor of said upper portion. aconduit for conducting condensate from the lower oi' said lower portionand-aconneetion between said portions,'said connection being accessiblefrom the vexterior a removable body forming a series o! intrictipnsbetween said two' portions.

15. In apparatus-oi' thek described atanxadaptedtoeontamanumtobe heated:a removable closure in the lower portion ci tank, acondenser for iiuidlcli a pipe coil having its'endsconnected to'oneninga in'saidclosure, avapor supply conduit connected to the openinz in the closure incommunication withtheinlet endotsaidunperportionacondensate return lineopening in said closure in communication with. the discharge end of saidlower portion, a passage in saidclosure connecting the discharge end ofthe upper portionand the inlet end roi' the lower ,a plurality o!densers tor heatina .fluid located in said means to conduct vapor fromsaid aenerator one of said condensers, a return line for conductingliquid from mother o! said con to the vapor aenerator.

means accessible from outside said tank. a re.- strietion in said returnline providing a smaller in saidY return line than in said vaporconducting means, and exoi sindV tank and 'comprising` laid.

'said relation with a conduit4 pansion means to said betherein and saidtank. 1 17'. Apparatusotthe character describedcomprising a sour-ceo!heat. a tank adapted'to cony.

tain a body to, be heated, a closed circuit for circulating a fluidbetween said source and tankpfsaid and means to relieve condenser. Y

18. Apparatus ofthe coin prising a source of heat, meansadapwdtocontainaboiiytobeheatedxneana` cloaedcircuit iorcirculatingaheaty nuid and transferring heat between said and said first named meam,namedtuto means comprising a vaporlenera acen source. a condenser inheat transmitting conducting vaportromthelenerator-tothe condenseranddensedvaporfromthecondemer tor, expansion means', an line connect-)areturnline'iorconductina conf area otsaidsvapor restriction beinglocat`v between means and the generator.

Gus'rsr' DALEN. ausrumm; 8.19m

